The present invention relates to a method for aligning macromolecules such as polymers or macro-molecules with biological activity, especially DNA, or proteins. The present invention also relates to the application of this method in processes for detecting
for measuring intramolecular distance, for separating and/or for assaying a macromolecule in a sample.
Controlling the conformation of macromolecules represents a major industrial challenge, for example in the manufacture of sensors or of controlled molecular assemblies, or alternatively in problems of detection and analysis. It may be useful to have an elongated molecular conformation. By way of example, in the case where polymers are grafted on a substrate, it has been proposed to extend them by the addition of an electric field, a flow or with the aid of optical tweezers. In particular, in biology, the alignment of DNA--by electrophoresis (Zimmermann and Cox Nucl. Acid Res. 22, p 492, 1994), free flow (Parra and Windle, Nature Genetics, 5, p 17, 1993 and WO 93/22463) or in a gel (Schwartz et al. Science 262, p 110, 1993 and U.S. Pat. No. 33531) or with the aid of optical tweezers (Perkins et al., Science 264 p 819, 1994 and also U.S. Pat. No. 5,079,169)--opens numerous possibilities in mapping, or in the detection of pathogens.
These methods only allow in general an imperfect alignment, or alternatively a transient alignment--that is to say that relaxation of the molecule occurs once the stress disappears. In the case of optical tweezers, the method is expensive, is limited to only one molecule at a time, and is difficult to carry out by non-qualified staff.
A special technique for aligning DNA by flow after cell lysis, followed by drying, has been proposed (I. Parra and B. Windle and WO 93/22463). The alignment obtained is very imperfect and nonhomogeneous and numerous nonaligned masses are observed.
The subject of the present invention is a novel and simple method for aligning macromolecules on the surface S of a support, characterized in that the triple line S/A/B (meniscus) resulting from the contact between a solvent A and the surface S and a medium B is caused to move on the said surface S, the said macromolecules having a part, especially an end, anchored on the surface S, the other part, especially the other end, being in solution in the solvent A.
It has been observed according to the present invention that the mere passage of a meniscus over molecules of which one part is anchored on a substrate, the remainder of the molecule existing freely in solution makes it possible to align them uniformly, perpendicularly to the moving meniscus, leaving them adsorbed on the surface behind the meniscus. This phenomenon is called "molecular combing" here.